The present disclosure relates to polycarbonate compositions that have increased flame retardance and reduced halogen content. Also disclosed are methods for preparing and/or using the same.
Polycarbonates (PC) are synthetic engineering thermoplastic resins derived from bisphenols and phosgene, or their derivatives. They are linear polyesters of carbonic acid and can be formed from dihydroxy compounds and carbonate diesters, or by ester interchange. Polycarbonates are a useful class of polymers having many desired properties, such as optical clarity, good impact strength, and higher heat distortion temperature (HDT).
Polycarbonate polymers and their blends with vinyl polymers are not inherently non-flammable. It is thus typically necessary to include flame retardant additives that retard the flammability of the resin and/or reduce dripping. Polytetrafluoroethylene (PTFE), particular fibrous PTFE, has long been used as an antidrip additive for many flame retardant applications. However, PTFE when burned will give off corrosive and toxic gases, including hydrofluoric acid (HF), which can be a danger to people and electronic equipment. Such halogenated flame retardants are also increasingly subject to regulatory restrictions. Reducing the halogen content while meeting flame retardance requirements typically involves the use of high molecular weight polycarbonates that reduce the flow of the polycarbonate and its blends. This reduction in flow properties makes their use more difficult in various manufacturing processes.
There remains a need in the art for non-halogenated flame retardant polycarbonate compositions that maintain their mechanical properties.